I think, for sub directories or nested directories permissions, using chmod -R option fixes the issue.
chmod -R 750 /var/lib/nova/instances chmod -R 750 /var/lib/nova/instances/_base
I think, for sub directories or nested directories permissions, using chmod -R option fixes the issue.
chmod -R 750 /var/lib/ nova/instances nova/instances/ _base
chmod -R 750 /var/lib/